1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
|
/* URL.java -- Uniform Resource Locator Class
Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004
Free Software Foundation, Inc.
This file is part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module. An independent module is a module which is not derived from
or based on this library. If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so. If you do not wish to do so, delete this
exception statement from your version. */
package java.net;
import gnu.java.net.URLParseError;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.StringTokenizer;
/*
* Written using on-line Java Platform 1.2 API Specification, as well
* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
* Status: Believed complete and correct.
*/
/**
* This final class represents an Internet Uniform Resource Locator (URL).
* For details on the syntax of URL's and what they can be used for,
* refer to RFC 1738, available from <a
* href="http://ds.internic.net/rfcs/rfc1738.txt">
* http://ds.internic.net/rfcs/rfc1738.txt</a>
* <p>
* There are a great many protocols supported by URL's such as "http",
* "ftp", and "file". This object can handle any arbitrary URL for which
* a URLStreamHandler object can be written. Default protocol handlers
* are provided for the "http" and "ftp" protocols. Additional protocols
* handler implementations may be provided in the future. In any case,
* an application or applet can install its own protocol handlers that
* can be "chained" with other protocol hanlders in the system to extend
* the base functionality provided with this class. (Note, however, that
* unsigned applets cannot access properties by default or install their
* own protocol handlers).
* <p>
* This chaining is done via the system property java.protocol.handler.pkgs
* If this property is set, it is assumed to be a "|" separated list of
* package names in which to attempt locating protocol handlers. The
* protocol handler is searched for by appending the string
* ".<protocol>.Handler" to each packed in the list until a hander is
* found. If a protocol handler is not found in this list of packages, or if
* the property does not exist, then the default protocol handler of
* "gnu.java.net.<protocol>.Handler" is tried. If this is
* unsuccessful, a MalformedURLException is thrown.
* <p>
* All of the constructor methods of URL attempt to load a protocol
* handler and so any needed protocol handlers must be installed when
* the URL is constructed.
* <p>
* Here is an example of how URL searches for protocol handlers. Assume
* the value of java.protocol.handler.pkgs is "com.foo|com.bar" and the
* URL is "news://comp.lang.java.programmer". URL would looking the
* following places for protocol handlers:
* <p><pre>
* com.foo.news.Handler
* com.bar.news.Handler
* gnu.java.net.news.Handler
* </pre><p>
* If the protocol handler is not found in any of those locations, a
* MalformedURLException would be thrown.
* <p>
* Please note that a protocol handler must be a subclass of
* URLStreamHandler.
* <p>
* Normally, this class caches protocol handlers. Once it finds a handler
* for a particular protocol, it never tries to look up a new handler
* again. However, if the system property
* gnu.java.net.nocache_protocol_handlers is set, then this
* caching behavior is disabled. This property is specific to this
* implementation. Sun's JDK may or may not do protocol caching, but it
* almost certainly does not examine this property.
* <p>
* Please also note that an application can install its own factory for
* loading protocol handlers (see setURLStreamHandlerFactory). If this is
* done, then the above information is superseded and the behavior of this
* class in loading protocol handlers is dependent on that factory.
*
* @author Aaron M. Renn <arenn@urbanophile.com>
* @author Warren Levy <warrenl@cygnus.com>
*
* @see URLStreamHandler
*/
public final class URL implements Serializable
{
private static final String DEFAULT_SEARCH_PATH =
"gnu.java.net.protocol|sun.net.www.protocol";
/**
* The name of the protocol for this URL.
* The protocol is always stored in lower case.
*/
private String protocol;
/**
* The "authority" portion of the URL.
*/
private String authority;
/**
* The hostname or IP address of this protocol.
* This includes a possible user. For example <code>joe@some.host.net</code>.
*/
private String host;
/**
* The user information necessary to establish the connection.
*/
private String userInfo;
/**
* The port number of this protocol or -1 if the port number used is
* the default for this protocol.
*/
private int port = -1; // Initialize for constructor using context.
/**
* The "file" portion of the URL. It is defined as <code>path[?query]</code>.
*/
private String file;
/**
* The anchor portion of the URL.
*/
private String ref;
/**
* This is the hashCode for this URL
*/
private int hashCode;
/**
* The protocol handler in use for this URL
*/
transient URLStreamHandler ph;
/**
* If an application installs its own protocol handler factory, this is
* where we keep track of it.
*/
private static URLStreamHandlerFactory factory;
private static final long serialVersionUID = -7627629688361524110L;
/**
* This a table where we cache protocol handlers to avoid the overhead
* of looking them up each time.
*/
private static HashMap ph_cache = new HashMap();
/**
* Whether or not to cache protocol handlers.
*/
private static boolean cache_handlers;
static
{
String s = System.getProperty("gnu.java.net.nocache_protocol_handlers");
if (s == null)
cache_handlers = true;
else
cache_handlers = false;
}
/**
* Constructs a URL and loads a protocol handler for the values passed as
* arguments.
*
* @param protocol The protocol for this URL ("http", "ftp", etc)
* @param host The hostname or IP address to connect to
* @param port The port number to use, or -1 to use the protocol's
* default port
* @param file The "file" portion of the URL.
*
* @exception MalformedURLException If a protocol handler cannot be loaded or
* a parse error occurs.
*/
public URL(String protocol, String host, int port, String file)
throws MalformedURLException
{
this(protocol, host, port, file, null);
}
/**
* Constructs a URL and loads a protocol handler for the values passed in
* as arugments. Uses the default port for the protocol.
*
* @param protocol The protocol for this URL ("http", "ftp", etc)
* @param host The hostname or IP address for this URL
* @param file The "file" portion of this URL.
*
* @exception MalformedURLException If a protocol handler cannot be loaded or
* a parse error occurs.
*/
public URL(String protocol, String host, String file)
throws MalformedURLException
{
this(protocol, host, -1, file, null);
}
/**
* This method initializes a new instance of <code>URL</code> with the
* specified protocol, host, port, and file. Additionally, this method
* allows the caller to specify a protocol handler to use instead of
* the default. If this handler is specified, the caller must have
* the "specifyStreamHandler" permission (see <code>NetPermission</code>)
* or a <code>SecurityException</code> will be thrown.
*
* @param protocol The protocol for this URL ("http", "ftp", etc)
* @param host The hostname or IP address to connect to
* @param port The port number to use, or -1 to use the protocol's default
* port
* @param file The "file" portion of the URL.
* @param ph The protocol handler to use with this URL.
*
* @exception MalformedURLException If no protocol handler can be loaded
* for the specified protocol.
* @exception SecurityException If the <code>SecurityManager</code> exists
* and does not allow the caller to specify its own protocol handler.
*
* @since 1.2
*/
public URL(String protocol, String host, int port, String file,
URLStreamHandler ph) throws MalformedURLException
{
if (protocol == null)
throw new MalformedURLException("null protocol");
protocol = protocol.toLowerCase();
this.protocol = protocol;
if (ph != null)
{
SecurityManager s = System.getSecurityManager();
if (s != null)
s.checkPermission(new NetPermission("specifyStreamHandler"));
this.ph = ph;
}
else
this.ph = getURLStreamHandler(protocol);
if (this.ph == null)
throw new MalformedURLException("Protocol handler not found: "
+ protocol);
this.host = host;
this.port = port;
this.authority = (host != null) ? host : "";
if (port >= 0 && host != null)
this.authority += ":" + port;
int hashAt = file.indexOf('#');
if (hashAt < 0)
{
this.file = file;
this.ref = null;
}
else
{
this.file = file.substring(0, hashAt);
this.ref = file.substring(hashAt + 1);
}
hashCode = hashCode(); // Used for serialization.
}
/**
* Initializes a URL from a complete string specification such as
* "http://www.urbanophile.com/arenn/". First the protocol name is parsed
* out of the string. Then a handler is located for that protocol and
* the parseURL() method of that protocol handler is used to parse the
* remaining fields.
*
* @param spec The complete String representation of a URL
*
* @exception MalformedURLException If a protocol handler cannot be found
* or the URL cannot be parsed
*/
public URL(String spec) throws MalformedURLException
{
this((URL) null, spec, (URLStreamHandler) null);
}
/**
* This method parses a String representation of a URL within the
* context of an existing URL. Principally this means that any
* fields not present the URL are inheritied from the context URL.
* This allows relative URL's to be easily constructed. If the
* context argument is null, then a complete URL must be specified
* in the URL string. If the protocol parsed out of the URL is
* different from the context URL's protocol, then then URL String
* is also expected to be a complete URL.
*
* @param context The context on which to parse the specification
* @param spec The string to parse an URL
*
* @exception MalformedURLException If a protocol handler cannot be found
* for the URL cannot be parsed
*/
public URL(URL context, String spec) throws MalformedURLException
{
this(context, spec, (URLStreamHandler) null);
}
/**
* Creates an URL from given arguments
* This method parses a String representation of a URL within the
* context of an existing URL. Principally this means that any fields
* not present the URL are inheritied from the context URL. This allows
* relative URL's to be easily constructed. If the context argument is
* null, then a complete URL must be specified in the URL string.
* If the protocol parsed out of the URL is different
* from the context URL's protocol, then then URL String is also
* expected to be a complete URL.
* <p>
* Additionally, this method allows the caller to specify a protocol handler
* to use instead of the default. If this handler is specified, the caller
* must have the "specifyStreamHandler" permission
* (see <code>NetPermission</code>) or a <code>SecurityException</code>
* will be thrown.
*
* @param context The context in which to parse the specification
* @param spec The string to parse as an URL
* @param ph The stream handler for the URL
*
* @exception MalformedURLException If a protocol handler cannot be found
* or the URL cannot be parsed
* @exception SecurityException If the <code>SecurityManager</code> exists
* and does not allow the caller to specify its own protocol handler.
*
* @since 1.2
*/
public URL(URL context, String spec, URLStreamHandler ph)
throws MalformedURLException
{
/* A protocol is defined by the doc as the substring before a ':'
* as long as the ':' occurs before any '/'.
*
* If context is null, then spec must be an absolute URL.
*
* The relative URL need not specify all the components of a URL.
* If the protocol, host name, or port number is missing, the value
* is inherited from the context. A bare file component is appended
* to the context's file. The optional anchor is not inherited.
*/
// If this is an absolute URL, then ignore context completely.
// An absolute URL must have chars prior to "://" but cannot have a colon
// right after the "://". The second colon is for an optional port value
// and implies that the host from the context is used if available.
int colon;
if ((colon = spec.indexOf("://", 1)) > 0
&& ! spec.regionMatches(colon, "://:", 0, 4))
context = null;
int slash;
if ((colon = spec.indexOf(':')) > 0
&& (colon < (slash = spec.indexOf('/')) || slash < 0))
{
// Protocol specified in spec string.
protocol = spec.substring(0, colon).toLowerCase();
if (context != null && context.protocol.equals(protocol))
{
// The 1.2 doc specifically says these are copied to the new URL.
host = context.host;
port = context.port;
file = context.file;
userInfo = context.userInfo;
if (file == null || file.length() == 0)
file = "/";
authority = context.authority;
}
}
else if (context != null)
{
// Protocol NOT specified in spec string.
// Use context fields (except ref) as a foundation for relative URLs.
colon = -1;
protocol = context.protocol;
host = context.host;
port = context.port;
file = context.file;
userInfo = context.userInfo;
if (file == null || file.length() == 0)
file = "/";
authority = context.authority;
}
else // Protocol NOT specified in spec. and no context available.
throw new MalformedURLException("Absolute URL required with null context");
protocol = protocol.trim();
if (ph != null)
{
SecurityManager s = System.getSecurityManager();
if (s != null)
s.checkPermission(new NetPermission("specifyStreamHandler"));
this.ph = ph;
}
else
this.ph = getURLStreamHandler(protocol);
if (this.ph == null)
throw new MalformedURLException("Protocol handler not found: "
+ protocol);
// JDK 1.2 doc for parseURL specifically states that any '#' ref
// is to be excluded by passing the 'limit' as the indexOf the '#'
// if one exists, otherwise pass the end of the string.
int hashAt = spec.indexOf('#', colon + 1);
try
{
this.ph.parseURL(this, spec, colon + 1,
hashAt < 0 ? spec.length() : hashAt);
}
catch (URLParseError e)
{
throw new MalformedURLException(e.getMessage());
}
if (hashAt >= 0)
ref = spec.substring(hashAt + 1);
hashCode = hashCode(); // Used for serialization.
}
/**
* Test another URL for equality with this one. This will be true only if
* the argument is non-null and all of the fields in the URL's match
* exactly (ie, protocol, host, port, file, and ref). Overrides
* Object.equals(), implemented by calling the equals method of the handler.
*
* @param obj The URL to compare with
*
* @return true if the URL is equal, false otherwise
*/
public boolean equals(Object obj)
{
if (! (obj instanceof URL))
return false;
return ph.equals(this, (URL) obj);
}
/**
* Returns the contents of this URL as an object by first opening a
* connection, then calling the getContent() method against the connection
*
* @return A content object for this URL
* @exception IOException If opening the connection or getting the
* content fails.
*
* @since 1.3
*/
public Object getContent() throws IOException
{
return openConnection().getContent();
}
/**
* Gets the contents of this URL
*
* @param classes The allow classes for the content object.
*
* @return a context object for this URL.
*
* @exception IOException If an error occurs
*/
public Object getContent(Class[] classes) throws IOException
{
// FIXME: implement this
return getContent();
}
/**
* Returns the file portion of the URL.
* Defined as <code>path[?query]</code>.
* Returns the empty string if there is no file portion.
*
* @return The filename specified in this URL, or an empty string if empty.
*/
public String getFile()
{
return file == null ? "" : file;
}
/**
* Returns the path of the URL. This is the part of the file before any '?'
* character.
*
* @return The path specified in this URL, or null if empty.
*
* @since 1.3
*/
public String getPath()
{
if (file == null)
return null;
int quest = file.indexOf('?');
return quest < 0 ? getFile() : file.substring(0, quest);
}
/**
* Returns the authority of the URL
*
* @return The authority specified in this URL.
*
* @since 1.3
*/
public String getAuthority()
{
return authority;
}
/**
* Returns the host of the URL
*
* @return The host specified in this URL.
*/
public String getHost()
{
int at = (host == null) ? -1 : host.indexOf('@');
return at < 0 ? host : host.substring(at + 1, host.length());
}
/**
* Returns the port number of this URL or -1 if the default port number is
* being used.
*
* @return The port number
*
* @see #getDefaultPort()
*/
public int getPort()
{
return port;
}
/**
* Returns the default port of the URL. If the StreamHandler for the URL
* protocol does not define a default port it returns -1.
*
* @return The default port of the current protocol.
*/
public int getDefaultPort()
{
return ph.getDefaultPort();
}
/**
* Returns the protocol of the URL
*
* @return The specified protocol.
*/
public String getProtocol()
{
return protocol;
}
/**
* Returns the ref (sometimes called the "# reference" or "anchor") portion
* of the URL.
*
* @return The ref
*/
public String getRef()
{
return ref;
}
/**
* Returns the user information of the URL. This is the part of the host
* name before the '@'.
*
* @return the user at a particular host or null when no user defined.
*/
public String getUserInfo()
{
if (userInfo != null)
return userInfo;
int at = (host == null) ? -1 : host.indexOf('@');
return at < 0 ? null : host.substring(0, at);
}
/**
* Returns the query of the URL. This is the part of the file before the
* '?'.
*
* @return the query part of the file, or null when there is no query part.
*/
public String getQuery()
{
int quest = (file == null) ? -1 : file.indexOf('?');
return quest < 0 ? null : file.substring(quest + 1, file.length());
}
/**
* Returns a hashcode computed by the URLStreamHandler of this URL
*
* @return The hashcode for this URL.
*/
public int hashCode()
{
if (hashCode != 0)
return hashCode; // Use cached value if available.
else
return ph.hashCode(this);
}
/**
* Returns a URLConnection object that represents a connection to the remote
* object referred to by the URL. The URLConnection is created by calling the
* openConnection() method of the protocol handler
*
* @return A URLConnection for this URL
*
* @exception IOException If an error occurs
*/
public URLConnection openConnection() throws IOException
{
return ph.openConnection(this);
}
/**
* Opens a connection to this URL and returns an InputStream for reading
* from that connection
*
* @return An <code>InputStream</code> for this URL.
*
* @exception IOException If an error occurs
*/
public InputStream openStream() throws IOException
{
return openConnection().getInputStream();
}
/**
* Tests whether or not another URL refers to the same "file" as this one.
* This will be true if and only if the passed object is not null, is a
* URL, and matches all fields but the ref (ie, protocol, host, port,
* and file);
*
* @param url The URL object to test with
*
* @return true if URL matches this URL's file, false otherwise
*/
public boolean sameFile(URL url)
{
return ph.sameFile(this, url);
}
/**
* Sets the specified fields of the URL. This is not a public method so
* that only URLStreamHandlers can modify URL fields. This might be called
* by the <code>parseURL()</code> method in that class. URLs are otherwise
* constant.
*
* @param protocol The protocol name for this URL
* @param host The hostname or IP address for this URL
* @param port The port number of this URL
* @param file The "file" portion of this URL.
* @param ref The anchor portion of this URL.
*/
protected void set(String protocol, String host, int port, String file,
String ref)
{
// TBD: Theoretically, a poorly written StreamHandler could pass an
// invalid protocol. It will cause the handler to be set to null
// thus overriding a valid handler. Callers of this method should
// be aware of this.
protocol = protocol.toLowerCase ();
if (! this.protocol.equals (protocol))
{
this.ph = getURLStreamHandler(protocol);
this.protocol = protocol;
}
this.authority = "";
this.port = port;
this.host = host;
this.file = file;
this.ref = ref;
if (host != null)
this.authority += host;
if (port >= 0)
this.authority += ":" + port;
hashCode = hashCode(); // Used for serialization.
}
/**
* Sets the specified fields of the URL. This is not a public method so
* that only URLStreamHandlers can modify URL fields. URLs are otherwise
* constant.
*
* @param protocol The protocol name for this URL.
* @param host The hostname or IP address for this URL.
* @param port The port number of this URL.
* @param authority The authority of this URL.
* @param userInfo The user and password (if needed) of this URL.
* @param path The "path" portion of this URL.
* @param query The query of this URL.
* @param ref The anchor portion of this URL.
*
* @since 1.3
*/
protected void set(String protocol, String host, int port, String authority,
String userInfo, String path, String query, String ref)
{
// TBD: Theoretically, a poorly written StreamHandler could pass an
// invalid protocol. It will cause the handler to be set to null
// thus overriding a valid handler. Callers of this method should
// be aware of this.
protocol = protocol.toLowerCase ();
if (! this.protocol.equals (protocol))
{
this.ph = getURLStreamHandler(protocol);
this.protocol = protocol;
}
this.host = host;
this.userInfo = userInfo;
this.port = port;
this.authority = authority;
if (query == null)
this.file = path;
else
this.file = path + "?" + query;
this.ref = ref;
hashCode = hashCode(); // Used for serialization.
}
/**
* Sets the URLStreamHandlerFactory for this class. This factory is
* responsible for returning the appropriate protocol handler for
* a given URL.
*
* @param fac The URLStreamHandlerFactory class to use
*
* @exception Error If the factory is alread set.
* @exception SecurityException If a security manager exists and its
* checkSetFactory method doesn't allow the operation
*/
public static synchronized void setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
{
if (factory != null)
throw new Error("URLStreamHandlerFactory already set");
// Throw an exception if an extant security mgr precludes
// setting the factory.
SecurityManager s = System.getSecurityManager();
if (s != null)
s.checkSetFactory();
factory = fac;
}
/**
* Returns a String representing this URL. The String returned is
* created by calling the protocol handler's toExternalForm() method.
*
* @return A string for this URL
*/
public String toExternalForm()
{
// Identical to toString().
return ph.toExternalForm(this);
}
/**
* Returns a String representing this URL. Identical to toExternalForm().
* The value returned is created by the protocol handler's
* toExternalForm method. Overrides Object.toString()
*
* @return A string for this URL
*/
public String toString()
{
// Identical to toExternalForm().
return ph.toExternalForm(this);
}
/**
* This internal method is used in two different constructors to load
* a protocol handler for this URL.
*
* @param protocol The protocol to load a handler for
*
* @return A URLStreamHandler for this protocol, or null when not found.
*/
private static synchronized URLStreamHandler getURLStreamHandler(String protocol)
{
URLStreamHandler ph = null;
// First, see if a protocol handler is in our cache.
if (cache_handlers)
{
if ((ph = (URLStreamHandler) ph_cache.get(protocol)) != null)
return ph;
}
// If a non-default factory has been set, use it to find the protocol.
if (factory != null)
{
ph = factory.createURLStreamHandler(protocol);
}
else if (protocol.equals("core"))
{
ph = new gnu.java.net.protocol.core.Handler();
}
else if (protocol.equals("file"))
{
// This is an interesting case. It's tempting to think that we
// could call Class.forName ("gnu.java.net.protocol.file.Handler") to
// get the appropriate class. Unfortunately, if we do that the
// program will never terminate, because getURLStreamHandler is
// eventually called by Class.forName.
//
// Treating "file" as a special case is the minimum that will
// fix this problem. If other protocols are required in a
// statically linked application they will need to be handled in
// the same way as "file".
ph = new gnu.java.net.protocol.file.Handler();
}
// Non-default factory may have returned null or a factory wasn't set.
// Use the default search algorithm to find a handler for this protocol.
if (ph == null)
{
// Get the list of packages to check and append our default handler
// to it, along with the JDK specified default as a last resort.
// Except in very unusual environments the JDK specified one shouldn't
// ever be needed (or available).
String ph_search_path =
System.getProperty("java.protocol.handler.pkgs");
// Tack our default package on at the ends.
if (ph_search_path != null)
ph_search_path += "|" + DEFAULT_SEARCH_PATH;
else
ph_search_path = DEFAULT_SEARCH_PATH;
// Finally loop through our search path looking for a match.
StringTokenizer pkgPrefix = new StringTokenizer(ph_search_path, "|");
do
{
String clsName =
(pkgPrefix.nextToken() + "." + protocol + ".Handler");
try
{
Object obj = Class.forName(clsName).newInstance();
if (! (obj instanceof URLStreamHandler))
continue;
else
ph = (URLStreamHandler) obj;
}
catch (Exception e)
{
// Can't instantiate; handler still null,
// go on to next element.
}
}
while ((! (ph instanceof URLStreamHandler))
&& pkgPrefix.hasMoreTokens());
}
// Update the hashtable with the new protocol handler.
if (ph != null && cache_handlers)
if (ph instanceof URLStreamHandler)
ph_cache.put(protocol, ph);
else
ph = null;
return ph;
}
private void readObject(ObjectInputStream ois)
throws IOException, ClassNotFoundException
{
ois.defaultReadObject();
this.ph = getURLStreamHandler(protocol);
if (this.ph == null)
throw new IOException("Handler for protocol " + protocol + " not found");
}
private void writeObject(ObjectOutputStream oos) throws IOException
{
oos.defaultWriteObject();
}
}
|